The Lewis structure of SO3 shows a central sulfur atom bonded to three oxygen atoms. The sulfur atom has six valence electrons, and each oxygen atom has six valence electrons. To satisfy the octet rule, the sulfur atom forms three double bonds with the oxygen atoms.

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O=S=O

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The VSEPR theory predicts that the molecular geometry of SO3 should be trigonal pyramidal. This is because the sulfur atom has three electron pairs that are bonded to atoms, and one lone pair of electrons. The three bonded electron pairs are arranged in a trigonal plane, and the lone pair of electrons is located at the top of the pyramid.

The bond angle in SO3 is 120 degrees. This is because the three oxygen atoms are arranged in a trigonal plane, and the lone pair of electrons on the sulfur atom repels the oxygen atoms, causing them to move closer together.

The SO3 molecule is polar because the sulfur atom is more electronegative than the oxygen atoms. This means that the electrons in the S-O bonds are pulled towards the sulfur atom, creating a partial positive charge on the sulfur atom and a partial negative charge on each of the oxygen atoms.

The dipole moment of SO3 is 1.61 D. This is because the three S-O bonds are arranged in a trigonal plane, and the lone pair of electrons on the sulfur atom is located at the top of the pyramid. This creates a net positive charge on the sulfur atom and a net negative charge on the three oxygen atoms.